Automatic v belt transmission



Dec. 19, 1950 w. R. BRAY AUTOMATIC v BELT TRANSMISSION Filed Nov. 29, 1946 Patented Dec. 19, 1950 U NIT ED STATE S. F F 2,534,409 I AUTOMATIC V BELT TRANSMISSION:

William R. Bray, Bryan, ,Tex.

Application November'29, 194G, Serial No.-712,9'45

4 Claims.--. (Cl. 74-.-230'.1Z)

l; Theinvention relates to an automatic V belt transmission.

An: object of the inventionis to provide a V' belt transmission: with drive and driven pulleys? having adjustable pulley groove widths;

Another object of the invention is to providea V belt transmission whereinthe pulleys oper ate as. a function of their rotative speed to adjust their pulley groove widths so as to position the'xv \belt'thereon. as a :function of the speed of rotation-ofthepulleys;

A further'object ofthe invention is to provide a :V belt transmissionwhereinthe v beltis positioned in the pulleygrooves so as t'oobtain-maximum starting torque.

A stilPftirther obje'ct of the invention is to pro vide a V-' belt' transmissionwherein the pulley groove widthisadjustableas a'iunction' of the ro-- tativezspeed of: the pulleys to-position th v belt thereon so as toobtainmaximurn power from the prime mover.

Afurthermbject of -the invention is to provide a :V- belt transmission witlidrive' and-- driven pill-'- leys wherein the V belt is positioned in the pulley grooves as a function of the rotative speed of the pulleysgthedriven pulley lagging slightly behind the drive -pulley during acceleration" soas to maintainthe V-belt taut.

Anotherobject ofthe invention' is to provide a V= belt transmission-havingthe" pulley; groove" widths adg'ustable by-double threaded screws operative as a functionoi the rotati-v'e speed 'of the pulleys to increase" or decrease the pulley groove Width:

A further object isto'providea- V- belt-transmission with adjustable pulleygroove widths, the

pulley grooves being adjustable by double threaded screws-securedtoone pulley half and an;

vide a -V belt tra-nsmission with drive and driven pulleys wherein-the V- belt' is positioned in the pulley grooves as afunction-of the rotative speed ofthe pulleys; the drive pulley lagging slightly behind thedriven pulley duringdeceleration so asto maintain the vbelt taut:

Other objects and advantages willbecome more apparentwith a consideration of the following description 1 considered in connection with the accompanying drawings -wherein'--- Fig; 1 ,is -a'fronti, plan view ofthe V- belt transmission showing the drive and: driven members instarting position;

Figi-2 isizar-sectionon line. -2i2-of: Fig; l showing the driven pulley with the centrifugally op erati-ve means thereon andi the connection-means fromithe endrplatesto thelslidableipulley half; I

Fig. 3 is -a.--sectionon 1ine -3-3 of Fig.- 1 show-= ing the drive cpulley withlthe-centrifugally oper -c able r-means thereon toadiust the. pu1ley;groove width asasfunctionrof the rotativesspeedjoilthe pulley;

In Fig; 3, the, prime mover 2- is connected ftothe drivepulley 3 by means .of the shaft 4'. ,i, A longi tudinal- -key 5 on=the outer :surface offlthe shaft engagesakeyway (i inbore 'l-Tof pulley 3..to posi:

tion the pulley to rotate with the shaft Thedrive pulley ,3tcomprises two beveledtplates, or pulley ,halves 8 and 9.

sion.

The" corresponding. pulley v portion 8 .-is; slidably mountedlonetheihuh lEther ii the pulleyhalit is connected'ontottheshaft l', it, is .slidably mounted onthe shaft Anend plate iifixedonhub it by pins. l 2}.which. hub is inturnsecuredtto the shaft fl 'asipreviously described; is..pr.0vided withgthe leverslS pivoted? at M -to the doublethreaded' screws il 5;..which screws pass through the holes I 6' provided'th'erefor, andjiinto the holeji'l'in pulley The screws 1 5 are providedl'withl-aright hand threaded portion is at the .upper end thereofito, engage-right'hand threadsliSfiri hole J55 of end plate I i. provided witha left hand threaded portion, 25 to engage the leithan'd threads 2 i of hole I? "in the,

pulle'yhalf 8.' A spring 22 disposed'between the endplate H andthe lever lt around screws. l5 tend'to retain-ithe screws J Bin outermost position, so that the. -V vb'elt 2 rides inwardly toward the, axis oferotation of the shaftlr whennthe prime mover iss-tarted. o

The sleverst 3- are :providedwith an upstanding:

portion 25 on the" outer-end thereof so=that as the -leVers l3' and 'to increase the sensitivity: of the leversin operation. the-tensiom spring 22 may be variedin strength,

or the Weights increased or decreased-- to vary w The pulley vhalf; fills; compelled to -rotate withthe shalt by akey-S and; a. keyway 6.; A lhubelfi'textends, from. .theipulley, half ,9'Land -is.;in.the form of a. cylindrical. exten-t The'lower endof the screw ltiisn It seems obvious that the range of sensitivity of the device as used with various sizes of prime movers.

The driven pulley is connected to a driven shaft 3'! by key 32 and key way 33 in the hub 35 of pulley half 36. The slidable pulley half 31 is similar to pulley half 8 of the drive pulley 3, and is likewise connected to the end plate 38 by a screw 39 having a right hand threaded portion 40 to engage a thread in hole 4| of the pulley half 37, and a left hand threaded portion to engage threads 42 of hole 43 in the plate 38.

The pins 44 through the collar of end plate 38 secures the end plate to the hub 35 which in turn is secured to the shaft by the key 32 as above described.

Levers 45, pivotally connected to the screws 39, have upstanding portions 43 and weights 4! thereon which are similar to the levers [3 previously described in regards to the drive pulley. A tension spring 53 positioned around the screws 39 between the end plate 38 and the slidable pulley half 31 tends to retain the levers in static position. The tension in such springs or the weight of the levers 45 may be varied to obtain different ranges of sensitivity.

It is to be noted that three centrifugal levers are shown on the end plates. However, it seems obvious that any suitable number may be employed to accomplish the desired result.

The device is so arranged, that as the prime mover is accelerating and during normal running, the driven pulley will lag slightly behind the drive pulley so that the V belt at all times remains taut. However, as the device is decelerated, the drive pulley lags behind the driven pulley so that the V belt remains taut during such deceleration.

As shown in the accompanying drawing, the V belt transmission assembly is in starting position. On the drive pulley, the spring 22 retains the levers [3 in an innermost position and the V belt is shown as riding inwardly in the groove towards the axis of rotation.

The V belt on the driven pulley is in opposite position with relation to that of the drive member. The levers are moved inwardly against the end plate 38 while the pulley half 31 has been moved inwardly by this action in conjunction with the left hand portion 42 moving out of hole 43 i This narrows the pulley in the pulley half 31. groove so that the V belt moves away from the axis of rotation of the pulley.

With the V belt close to the axis of rotation of the shaft 4 of the prime mover, maximum starting torque of the prime mover is thereby utilized to effect rotation of the driven shaft.

As the driven pulley picks up speed from the drive pulley, levers 45 pivot outwardly so as to rotate screw 39 in such a manner that the screw moves into the hole 4! of pulley half 31 while moving outwardly through the hole 43 of end plate 38, the net result being that slidable pulley half 37 recedes from pulley half 36 so that the pulley groove width will increase, causing the V belt to move in toward the axis of rotation.

Similarly, slidable pulley half 8 of the drive pulley moves toward pulley half 9 when the pulley reaches a predetermined speed so that the levers i3 pivot outwardly as seen in dotted line in Fig. 1.

In this manner, a V belt transmission system is provided wherein, maximum starting torque of the prime mover is utilized at starting and the rotative speed of the pulleys is used to position 4 the V belt in the groove of the pulley. The hub It! could be eliminated by connecting the pulley half 9 directly onto the shaft 4.

Broadlylthe invention contemplates a V belt power transmission assembly including drive and driven pulleys wherein the rotation of the pulleys is utilized to position the V belt in the pulley grooves.

The invention claimed is:

.1. A V belt transmission comprising drive and riven pulleys, each of said pulleys including a pair of beveled plates forming a pulley groove therebetween, means to adjust the width of the pulley groove so as to determine the position of the V belt thereon as a function of the speed of rotation of the pulley comprising a member mounted in spaced relation to said beveled plates, a lever on said member, said lever being movable by centrifugal force, and means connecting said member to one of said pulley plates to adjust the relative position of said plates as a function of the rotative speed, said means including a threaded screw connected to said lever and passing through said member into said pulley plate, the threads on one end thereof being opposed to the threads on the opposite end thereof, whereby rotation of said lever by centrifugal force rotates said screw so as to move said connected pulley half.

2. A V belt transmission comprising, drive and driven shafts, means to rotate said drive shaft, a pulley half mounted on each of said shafts, a second pulley half slidably mounted on each of said shafts and forming a pulley groove with said first pulley half, means to adjust the distance between said pulley halves so as to determine the position of a V belt thereon as a function of the speed of rotation of the pulley comprising, a member mounted on each of said shafts, means to connect said member to said slidable second pulley half, an additional means on said member secured to said connecting means and movable by centrifugal force to adjust the relative position of said pulley halves as a function of the rotative speed.

3. A V belt transmission comprising, drive and driven shafts, pulleys mounted on said shafts, said pulleys each including a pair of beveled plates forming a pulley groove therebetween, one of said plates being slidably mounted on each of said shafts, means to adjust the width of the pulley groove so as to determine the position of the V belt thereon as a function of the speed of rotation of the pulley comprising, a member mounted on said shaft and threadedly connected to said slidable plate, a portion of said member movable by centrifugal force to move said plate along said threaded connection to adjust the relative position of said plates as a function of the rotative speed.

4. A V belt transmission comprising, a shaft, a pulley half mounted on said shaft, a second pulley half axially slidable relative to said first pulley half forming a pulley groove therebetween, means to adjust the width of the pulley groove by changing the relative axial position of said halves so as to determine the position of the V belt thereon as a function of the speed of rotation of the pulley comprising, a member mounted to rotate with said pulley, means connecting said member to said second pulley half, means on said member secured to said connecting member movable by centrifugal force, said connecting means including a threaded screw passing through said member and into said second pulley half, the

threads on one end thereof being opposed to the threads on the opposite end thereof whereby rotation of said means movable by centrifugal force rotates said threaded connecting means to adjust the relative position of said pulley halves as a function of the rotative speed.

WILLIAM R. BRAY.

REFERENCES CITED The following references are of recordin the file of this patent:

Number Number 6 UNITED STATES PATENTS Name Date Ross Apr. 16, 1935 Weston May 9, 1939 Heyer Sept. 1, 1942 Steven Apr. 20, 1943 Magee Aug. 29, 1944 Salsburg May 6, 1947 FOREIGN PATENTS Country Date Great Britain May 31, 1905 

